针对传统的液晶显示器应用于一些驾驶舱时存在的特殊观看视角问题, 设计了一种新型的光学膜, 以使液晶显示器的最大亮度可根据观看者的位置实现特定角度的偏转。首先, 基于现有背光的配光曲线, 提出光学膜表面微结构为直角三角形; 考虑由于直角边的全反射, 半光强视角范围较窄且存在截止角, 对微结构进行了棱高和角度的优化设计, 使半光强处视角范围得到提高。为消除截止角并进一步增大半亮度视角范围, 对微结构再次进行优化设计, 提出了双峰折线形非对称的光学膜表面微结构。仿真结果表明: 水平视角不变时, 偏转膜垂直方向最大亮度在20°处, 透过率为87.3%, 半亮度视角为(-12.5°, 45°)。根据设计结果加工了实际样品并进行了实验测试, 测试结果表明: 与传统的背光视角相比, 偏转膜垂直方向最大亮度由原来的0°偏转到18.9°, 半亮度视角由(-24.1°, 23.5°)变为(-9.2°, 45.3°), 透过率为82.0%, 满足了特定视角的观看要求。

When a liquid crystal display is used in cockpits, its max luminance direction usually has a certain angle with the direction of viewers. Therefore, this paper designs an optical film with a microstructure surface to allow the max luminance to be changed with the direction of viewers. Based on the luminous distribution of common backlight, the microstructure surface of the optical film was designed as a right triangle. In consideration of the total reflection of the right-angle side, narrower half-luminance angle range and its cut-off angle, the height and the angle of the microstructure were optimized to improve the half-luminance angle ranges. To eliminate cut-off angle and to increase half-luminance angle ranges further, the microstructure was optimized once again, and the outline with two peaks for the microstructure was proposed. The simulation results show that when the horizontal viewing angle doesnt change, the vertical viewing angle is at about 20°, the transmittance is 87.3% and the half-luminance angle ranges are (-12.5°, 45°). On the basis of the design, a sample was produced and measured. The practical measurement results show that the angle of max luminance turns from 0° to 18.9°, the half-luminance viewing angle changes from (-24.1°, 23.5°) to (-9.2°, 45.3°), and the transmittance is 82.0% as compared with the common backlight without the optical film. These results satisfy the requirements of special viewing angles.